<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>form表单的JS操作</title>
</head>

<body>
    <div>
        <input id="username" type="text" name="username" placeholder="请输入用户名" maxlength="20">
        <input type="password" name="pwd" autocomplete="off" required>

    </div>
</body>

</html>